Influence of nitrogen pre-implantation on deuterium retention in tungsten

The influence of nitrogen (N) pre-implantation on the deuterium (D) retention in tungsten (W) at different temperatures was investigated.Bulk W samples were exposed to D plasma with a fluence of 110 24 D/m 2 with or without nitrogen pre-implantation at 300 K and 500 K, respectively.Nuclear reaction analysis was applied for the determination of N content and D retention in the near surface.Optical microscopy was used to investigate the surface modification by blistering after implantation.It is shown that, the W:N layers formed during the N preimplantation play very different roles on D retention and blistering in the samples at different temperatures.At 500 K, the W:N layer seems to enhance D diffusion into the bulk by suppressing D loss from the surface, which results in a much higher D concentration in the bulk and larger blisters than without N pre-implantation.At 300 K, the effect of this layer is much less pronounced than that at 500 K.